U.S. manufacturing giants voiced cautious optimism over the weekend that a slow economic recovery is under way.

Top U.S. officials wooed the powerful leaders of the National Association of Manufacturers at the group's annual winter meeting at a plush seaside retreat, calling for support of President Bush's recovery plan for an economy they claim is showing some signs of improvement.But Peter D. Hart, a Washington-based pollster who recently completed an image focus study for the 12,500-member organization, ended the executives' three-day conference with sobering forecasts.

A recent Hart poll indicates that 63 percent of Americans believe the country is in a "state of decline."

Nearly 40 percent have experienced unemployment, either directly or through a family member. And 63 percent believe most U.S. politicians are crooked, Mr. Hart said.

"People are furious at what's happening. There is a lot festering out there," he said. "People are scared. For 1992, this is a country that wants big changes."

Last year, 65 percent of Americans believed the country was headed in the right direction; today only 18 percent feel that way, Mr. Hart said.

"Never in the history of polling have I seen such a dramatic change," he noted.

While business likely will remain sluggish or flat throughout the year, many of the manufacturing executives are hopeful.

Jeff Coors, president and chief executive officer of Coors Technology Cos. in Golden, Colo., expects overall "fairly modest growth," with strong expansion in his aluminum and packaging divisions.

Last year, the federal excise tax "really clobbered us," Mr. Coors said, noting the tax increased the price of beer by $1.20 a case.

Dexter F. Baker, chairman and chief executive officer of Air Products and Chemicals Inc., Allentown, Pa., said his company will increase investment 10 percent to 15 percent above previous projections and will begin implementing a $100 million backlog of projects that were on hold.

"There are significant opportunities for the chemical industry, especially in Japan," said Mr. Baker, who also is chairman of NAM and who accompanied President Bush on his recent trip to Australia and Asia.

Earlyn Church, vice president of Superior Technical Ceramics in St. Albans, Vt., recently laid off six of 90 employees - her first layoff in 15 years.

"We're seeing bad cash flow. We've still got orders, but we're seeing companies space out orders," Ms. Church said. "We're not putting in a lot of big machine orders."

Ron Sandmeyer, president of Sandmeyer Steel Co. in Philadelphia, said 1992 ''is going to be flat. I share that feeling with the customers we talk with. There are some indicators the economy may turn around, but I don't think it's going to be significant."

Charles Walker, executive vice president and chief financial officer at

Ethyl Corp. in Richmond, Va., said his company still is smarting from slowdowns that began a year ago.

"We don't see any immediate turnaround although we are optimistic," Mr. Walker said. "There will be a slow recovery. There's no outright pessimism but there's not a groundswell of optimism, either."

The defense industry will be hit hard, said Philadelphia-based Lavelle Aircraft's Dick Ludwig, bemoaning President Bush's proposed defense cuts.

"What does the government intend to do to replace that part of the economy? And the Democrats say we need even more defense cutbacks," Mr. Ludwig said.

"We need replacement for a major industry that is being wiped out."